Straightening
To knock out small dents with a straightening hammer, while holding a manual anvil on the opposite side. Do not knock too hard, otherwise the metal will stretch and not acquire a smooth surface. Work evenly, moving from the edges to the middle of the damaged area.
Constantly feel the straightened surface with your hand until it acquires the desired shape. Small irregularities are subsequently removed with putty.
After straightening, carefully remove rust and old paint. Or coarse sandpaper (grain 120), put on a wooden block, or with the corresponding sanding sheets on the grinding wheel. Close decorative moldings and plastic parts located nearby with a protective film so as not to scratch them by negligence.